Using ammonium molybdate and thiourea as precursors, nitrogen-doped MoO₃ was produced by a one-step carbonization and then fixed into the cellulose filter paper (NMCP) with acrylic resin as a fixative. NMCP was designed as a multifunctional nanocomposite, i.e., solid phase adsorbent for Fe(III) preconcentration, photocatalyst for iron species transformation and color interference removal, and colorimetric sensor for Fe(III) determination. After photocatalysis, the complex of Fe-humic substances could be transformed into Fe(III) ions, the interference of colored organic matter (e.g., aqueous humic substance) was removed, Fe(III) was enriched selectively onto NMCP with the coexistence of interference metal ions (e.g. Co(II) and Cd(II)) and then transformed into Fe(II) by hydroxylamine and photoreduction and for colorimetric analysis. The obstacle of o-phenanthroline colorimetric method was overcome. The photodegradation activity of MoO₃ was improved 2.02 times by nitrogen doping with the optimal mass ratio, which was also 5.11 times of P25-TiO₂. The concentration of Fe(III) on NMCP was quantified by the gray-scale using smart phones and image processing software, without complicated equipment. Based on multifunctional NMCP, a fully integrated visual analysis system was proposed and suitable for the field detection of Fe(III) in natural water. The log-linear calibration curve for Fe(III) was in the range of 0.05–5 mg/L with a determination coefficient (R²) of 0.976 and detection limit of 15 μg/L.

以钼酸铵和硫脲为前体，掺氮MoO ₃通过一步碳化将其制成，然后用丙烯酸树脂作为固定剂将其固定在纤维素滤纸（NMCP）中。NMCP被设计为多功能纳米复合材料，即用于Fe（III）预浓缩的固相吸附剂，用于铁物种转化和颜色干扰消除的光催化剂以及用于Fe（III）测定的比色传感器。光催化后，腐殖质中的铁可以转化为Fe（III）离子，去除了有色有机物（例如腐殖质水溶液）的干扰，Fe（III）选择性地富集到NMCP上，并与干扰共存。金属离子（例如Co（II）和Cd（II）），然后通过羟胺和光还原法转化为Fe（II），用于比色分析。克服了邻菲咯啉比色法的障碍。通过以最佳质量比进行氮掺杂，将₃提高了2.02倍，也是P25-TiO _2的5.11倍。使用智能手机和图像处理软件，无需复杂的设备，即可通过灰阶对NMCP上的Fe（III）浓度进行定量。基于多功能NMCP，提出了一种完全集成的可视化分析系统，适用于天然水中Fe（III）的现场检测。Fe（III）的对数线性校准曲线在0.05-5 mg / L的范围内，测定系数（R ²）为0.976，检测极限为15μg/ L。